The isostatic pressure graphite is a kind of new graphite material. Because it have a series of and good characteristic, from but make it with the high and nwe technique of the now, the sophisticated technique in national defense is join close mutually. It is graphite crystallize machine that single crystal silicon furnace in manufacturing that material, the metals continuum casting the electricity spark processes to use graphite eletrode can't substitute etc. Also is extremely good material for make a fire pole of the rocket, encourage the pole and spray the mouth with the rudder plank,and a deceleration materials and reflect materials in the graphite nuclear reactor.
Carbon graphite materials in the manufacturing process, due to the different molding methods, the performance of different directions will be different. Mainly manifested in: resistivity, thermal conductivity, mechanical properties, thermal expansion coefficient, etc.. The general method for the determination of the products is: according to the pressure surface vertical direction and horizontal direction on the pressure surface sampling properties were determined, and then using the least square data, divided by the maximum side of the data, we can get the isotropic ratio. Usually calculated by the determination of the coefficient of expansion.
For the manufacture of fine structure, dense texture, uniform microstructure of carbon graphite materials, using powder (rather than paste) is the only way. And the pressing method and the static pressure method are used to press the powder. In the molding process, either a single or double pressing pressing, the friction force (carbon particles and products between the mold and the influence of the pressure transfer) will be gradually reduced, resulting in uneven density. This difference increases with the increase of the height of the product.
When using the static press molding, the product is uniform in all directions, the volume density is uniform, and is not limited by the height of the product
Many reasons for roasting products cracking, such as formula rationality, binder amount, unit pressure, baking curve speed, the uniformity of heating products and roasting process of "leaching of low temperature oxygen", filling material properties and so on, but it is undeniable that the uneven density volume is one of the products. The main culprit defect inside the product structure caused by roasting cracking. This is because the volume density is different, there are differences in the expansion coefficient, in the roasting process, the internal stress will be generated. When the stress exceeds the strength of the product itself, it will crack due to internal stress. This cracking is not only produced in the roasting process, but also is easy to produce in the cooling process.
